A retrospective study of correlation of morphologic patterns, MIB1 proliferation index, and survival analysis in 134 cases of plasmacytoma

Plasmacytoma classified into solitary plasmacytoma of bone (SPB) and extramedullary plasmacytoma (EMP) is characterized by infiltrate of plasma cells of diverse maturity and by their monoclonal immunoglobulin products. Both SPB and EMP represent different groups of neoplasm in terms of location, tumor progression, and overall survival rate. There is a need for features that indicate likelihood of myeloma in patients with plasmacytoma without other manifestations. This study was an attempt to study the morphologic patterns of plasmacytoma (SPB and EMP), MIB1 proliferation index, and correlation of these with clinicopathologic features and survival of the patients. The study group comprised of 134 cases of plasmacytoma (88 SPB and 46 EMP) over duration of 8 years and were graded as per Bartl's histologic grading system. Commonest site was vertebral body in SPB (36%) and upper aerodigestive tract in EMP (48%). On serum electrophoresis, overall M band was detected in 41% cases. Both SPB and EMP on histology revealed similar morphologic features. MIB1 proliferation index ranged from less than 1% to 80%. It was slightly higher in EMP in comparison with SPB (P value = .002). Seventy percent of cases, which progressed to multiple myeloma (MM) showed MIB1 labeling index more than 10%; however, it was not statistically significant in predicting the disease progression. With the median follow-up of 19 months (range, 1-99 months), 10 SPB had disease progression of which 7 converted to MM, and 3 developed EMP, with a median interval of 21 months (range, 8-75 months) for the development of MM and 3 months (range, 3-9 months) for the progression to EMP. Five-year survival for EMP varied by site, with poorest survival in brain/central nervous system EMP as compared with EMP at other sites. To conclude, grade and MIB1 proliferation index help in predicting aggressive course in plasmacytoma.

Cyclin D1 expression in multiple myeloma by immunohistochemistry: Case series of 14 patients and literature review

Background:

Cyclin D1 dysregulation is an early and unifying oncogenic event in patients of multiple myeloma (MM). This may be detected up to 30% cases by immunohistochemistry (IHC) and up to 40-50% cases by molecular studies. However, studies on the clinical significance of cyclin D1 dysregulation in MM have been inconclusive. We aimed to study the pattern of cyclin D1 expression in MM by IHC and correlate with selected clinicopathologic features.

Materials and Methods:

Formalin fixed, decalcified, bone marrow trephine sections from 14 symptomatic patients of MM (13 newly diagnosed and one relapsed) were subjected to cyclin D1 IHC by using a rabbit monoclonal antibody to cyclin D1 (clone EPR2241).

Results:

Cyclin D1 expression (in ≥10% tumor cell nuclei) was observed in 8 of 14 cases (57%). Cyclin D1 positive (+) group had significantly lower hemoglobin level (P = 0.03) than cyclin D1 negative (−) group (n = 6); though both groups showed no statistical significance (P > 0.05) in regard to age, gender, Durie and Salmon stage, lytic bone lesions, light chain phenotype, creatinine, calcium, lactate dehydrogenase, leukocyte and platelet count and bone marrow histology. Ten of 14 (71.5%) showed a favorable response (follow-up; 7 days to 34 months) to thalidomide and/or bortezomib based chemotherapeutic regimen. Four of eight cyclin D1− patients showed complete response, two had a partial response (PR) and two died of the disease; whereas 4/6 cyclin D1 − patients had PR, one refused definitive therapy and one was lost to follow-up (P > 0.05, Fischer's exact test).

Conclusion:

IHC may be a feasible tool for the demonstration of cyclin D1 expression on adequately processed trephine biopsy specimen in MM patients in a resource poor setting. Negative IHC results should be correlated with molecular techniques for prognostication.